The present invention relates to a winding spindle for mounting a plurality of winding tubes on a yarn winding machine. A winding spindle of this general type is disclosed in DE 196 07 916 A1.
Winding spindles of this type are used in winding or takeup machines for winding freshly spun synthetic filament yarns to packages. To this end, a plurality of winding tubes are mounted, one after the other, on the winding spindle that is projectingly arranged in the takeup machine. For mounting the winding tube, the winding spindle possesses a clamping device that includes a plurality of clamping elements, which are adapted for extending radially outward. For receiving the clamping device, an annular space is formed between an outer tube and an inner tube.
The inner tube connects to a drive shaft for transmitting the rotational motion, and the outer tube is coupled with the inner tube in a substantially formfitting manner, with the load capacity of the winding spindle being defined by the inner tube. As a result, the known winding spindle has a relatively small, bending-critical natural frequency. To realize high yarn speeds of more than 4,000 m/min, the winding spindle must operate as a function of the package diameter in a speed range from about 2,000 to 22,000 rpm while winding the yarns. In this process, the natural frequencies of the winding spindle represent to a certain extent critical speeds, which lead to resonance vibrations. It is therefore desired to design the winding spindle in such a manner that it reaches a natural frequency that is as high as possible. In this connection, however, it is necessary to maintain the inside diameters of the tubes being mounted as the extreme limit values for the configuration of the winding spindle.
EP 0 704 400 discloses a winding spindle wherein the outer tube is constructed as a supporting element and coupled with a drive. Winding spindles of this type, however, have in general the disadvantage that the connection to a drive must be initiated at the end of the outer tube because of the internally arranged clamping device. With that, high torsional moments are additionally introduced into the outer tube. This requires an additional torsional rigidity besides the desired high flexural strength.
It is therefore an object of the invention to further develop a winding spindle of the initially described type in such a manner that the natural frequency of the winding spindle is increased to a substantial extent.